A known towing mechanism is shown in U.S. Pat. No. 7,048,294, which issued in May 2006 and which is assigned to the assignee of this application. This mechanism is designed for use with a utility vehicle, such as an agricultural tractor. This known towing mechanism includes an upper bracket, a lower bracket and a locking device. Such lower brackets are also referred to as tractor drawbars, and such upper bracket are referred to as a hammerstrap.
An implement drawbar is received between the two brackets and retained by a towing bolt which is received in bores in the brackets. The locking device includes a locking pin which slides axially in a pin bore. The locking pin projects from the pin bore and engages and prevents axial movement of the towing bolt. The locking pin includes a loop-shaped spring which prevents unintentional axial sliding of the locking pin. However, this spring is not designed to resist forces acting on the locking pin in the axial direction of the locking pin, such as caused by a foreign object. Such forces can bend the spring and move the locking pin to an unlocked position freeing the towing bolt. Thus, it would be desirable to provide such a towing mechanism which reduces the risk that a drawbar coupled to the towing mechanism could be released. In order to avoid this possibility, the spring could be made stronger, but this would make the operation of the locking arrangement considerably more difficult.